Improvement in screw-propellers



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N. A. PATTERSON. Screw-Propellers;

Patented Oct. 27, 1874.

INVENTOR WITNESSES a-M fem @(QGM Attorney;

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4Sheets--Shee t 4 N. A. PATTERSON. Screw-Propellers.

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WITNESSES v INVENTOR jywd y i THE GRAPHIC CO. ENOYO-LITHJSQi 44 PARK PLACEJLY. I

UNITED STATES PATENT OFFICE.

NEWTON A. PATTERSON, OF CLEVELAND, TENNESSEE.

IMPROVEMENT IN SCREW-PROPELLERS.

Specification forming part of Letters Patent No. 156,375, dated October 27, 1874 application filed May 15, 1874.

To all whom it may coiw'em:

Be it knownthat I, NEWTON A. PATTER- soN, of Cleveland, in the county of Bradley and State of Tennessee, have invented an Improvement in Propellers, of which the following is a specification:

Inthis invention each blade of the screw is made straight, or nearly so, at its forward or cutting edge, and has a gradually-increasing radial curvature, imparting to the forward section formand proportions similar or analogous to those of a helicoid'al blade of most ap-- proved form. From the outer portion of this forward section a flange or lobe projects backward, having a spiral or increasingcurvature to prevent centrifugal movement or slip of the water leaving an open space within the rear lobes around the shaft.

My invention combines all the advantages of a helicoidal blade with the centrifugal properties of my propeller patented August 26, 187 3.

In the accompanying drawings, Figure 1 is a rear View of a three-bladed screw illustrating my invention. Fig. 2 is a rear-edge view of one of the blades. Fig. 3 is an elevation of a blade looking in a direction perpendicular to the surface. Fig. 4 is a section on the line 4 4, Fig. 3". Fig. 5 is a rear view of a blade of modified form. Fig. 6 is a transverse ting edge a of each blade is straight, or near- 1y so, viewed edgewise or in the direction in which it cuts the water, but may have a curved outline, as indicated by dotted lines 6 in Figs. 1 and 5, or full lines in Fig. 9. From this edge the blade takes a spiral form with gradually-increasing curvature from center to circumference, so that the section bounded by the lines a b {approximate closely to the form of improved helicoidal blades now in use. From the line b a lobe or fiange,. c, extends backward, continuing the spiral or increasing curvature of the outer portion of the blade in such a manner as to still confine the water against tangential slip, and cause the blade to act on it with full effect. Between this lobe or flange and the shaft S is a space, d, permitting the passage of *water at the center of the wheel.

The length of the lobes a may be varied according to the number of blades and the size of the wheel.

In wheels of small size having a rapid rotation the curvature of the blades toward the periphery is more abrupt or rapid than in larger wheels haying a slower movement.

The following is claimed as new:

A screw-propeller with blades having helicoidal front parts a b, backwardly-projecting lobes c, of greater concavity or curvature, and throats d, to permit the passage of water at the center, all substantially as herein shown and described.

In testimony of which invention I hereunto set my hand this 15th day of April, 1874..

N. A. PATTERSON. Witnesses:

OGTAVIUS KNIGHT, WALTER ALLEN. 

